Question

1. In 1974, Loftus and Palmer conducted a classic study demonstrating how the language used to ask question can influence eyewitness memory. In the study, college students watched a film of an automobile accident and then were asked questions about what they say. One group was asked, “About how fast were the cars going when they smashed into each other?” Another group was asked the same question except the verb was changed to “hit” instead of “smashed into.” The “smashed into” group reported significantly higher estimates of speed than speed than the “hit” group. Suppose a researcher repeats this study with a sample of today’s college students and obtains the following results.

Estimated Speed

Smashed into	Hit
n=15	n=15
M=40.8	M=34.0
SS= 510	SS= 414

Using a one-tailed test with α = .01, determine whether the “smashed into” group estimated significantly higher speed than the “hit” group.

a) State the null hypothesis in words and in a statistical form.

b) State the alternative hypothesis in words and a statistical form.

c) Compute the appropriate statistic to test the hypotheses. Sketch the distribution with

the estimated standard error and locate the critical region(s) with the critical value(s).

d) State your statistical decision

e) Compute Cohen’s d. Interpret what the d really means in this context.

f) What is your conclusion? Interpret the results and describe in words.

Answer 1